It will be worthwhile to test the X1900GT and X1800GTO. Dongle-less Crossfire depends entirely on the PCIe interface for inter-card communication; it may expose a significant bottleneck in the 965 board's PCIe x4 slot. And realistically, many users who decided to save a few bucks with a 965 board will probably want to use these mainstream cards.

I have also heard somewhere that running two X1900GTs in Crossfire requires a RD580 board. Always wondered if it's true, because then Conroe users effectively lose this option. Reply

This was more of a forward looking statement (already addressed the unofficial SLI driver situation) and also to address any issues with readers saying they can run SLI on their Intel boards now. If NVIDIA and Intel ever come to an agreement then the statement holds true, if you decided to run the unofficial SLI drivers on the P965 then the overhead from the hacked drivers along with the DMI slowdown will create a performance delta between the 975X and P965. Reply

Gary, nice article. I think it is the first time I see a comparison on the performance hit caused by the x4 bottleneck. It would be interesting also to see in a future article how does a pair of 7900 GTXs running in SLI using the hacked drivers stacks against the XFire solution.

I wonder if this move will drive Nvidia in the future to allow also SLI on the 975 or 965 chipsets. We know it can be done, perhaps it is a commercial or licensing problem that is blocking it. Reply

Hell no! Not for this type of article - leave the scaling graphs in place. I would much rather see one graph (with numbers below) showing how cards scale from 1280x1024 through 1920x1200 instead of three separate graphs. Single bar charts are only effective when showing one data set. Reply

Does overclocking the FSB (holding memory and cpu clocks constant) help alleviate some of the bandwidth and timing issues? Or, does overclocking the FSB not affect transfer rates between the MCH and ICH?

If the latter is the case, then who will be the first manufacturer to step up with MCH/ICH bus overclocking?

Any thoughts from the anandtech folks about a follow up article, or have you already tried increasing the FSB? Reply

I am working on the overclocking aspects today. I just received the final bios code so I will update the article this weekend if there is a significant change in performance when overclocking both chipsets. If not, I will comment on it in here. Reply

Skimp on the motherboard? If you buy an E6400 and want to overclock you would not get a 975x board anyway. You would get a 965 board because they achiegve much much higher FSB. It's not going cheap at all, it's actually playing smart. Reply

No? Thanks for telling me, and everyone else what we'd do . . . The latest ABIT 975x board is looking rather attrative, and I know I'm not alone here. Anyhow, why would I step backwards in time, for overclocking, especially when the added performance boost really isnt worth it ? Memory compatability issues ? Lack of SLI support ? I think I'll spend a little more for current technology.

It's only playing it smart, if all you care about is overclocking. Alot of us who are enthuiasts, also care about stability, which means the system in question needs to be up for more than a few days. All my systems MUST be up for months at a time, and if they dont 'pass' this qualification *something* changes until they do. Its been my experience that systems pushed to the edge, often only exibit at best, a few days up time before a crash. Often times, this behavior includes mild overclocks aswell.

In a word, NVIDIA. All they need to do is support SLI on non-NVIDIA chipsets and it would work. SiS did a driver hack a while ago for their chipset, but NVIDIA nuked that with the next driver release... and bought up SiS just for good measure. Reply